1. Field of the Invention
This invention relates to rotary drives and concerns a device for limiting the number of revolutions of a shaft for rotary drives of sliding roofs in automobiles.
2. Description of the Related Art
Typically, a device for limiting the number of revolutions of a shaft for rotary drives of sliding roofs in automobiles, comprises an actuating crank consisting of crank base (4) and crank arm (5), the crank base (4) of which engages force-transmittingly on the shaft (1) and the crank arm (5) of which is connected in articulated manner to the crank base by a pivot pin (6), and comprising an eccentric disc (14), rigidly fixed to the shaft (1), on the circumferential surface of which (disc) there is rotatably journalled a toothed ring (16) provided with an external set of teeth (15), which is surrounded by an internal set of teeth (17) disposed fixed in a rose (7) and concentrically to the shaft axis, the tooth foot radius (dedendum radius) of which is greater than the tooth crest radius (addendum radius) of the toothed ring (16) approximately by the amount of the eccentricity of the eccentric disc (14), wherein abutment means for the limiting positions of the shaft (1) after a predetermined number of revolutions have been reached are connected, on the one hand with the toothed ring (16) and on the other hand with the rose (7), and wherein the abutment means connected with the rose (7) is a blocking pin (19) displaceably guided parallel to the shaft, which (blocking pin) can be engaged (retracted) into the path of the counter-abutment means connected with the toothed ring or disengaged (extended) from it by spring force only in at least one specific position of the toothed ring (16), in the engaged (retracted) position releases both directions of rotation of the drive and in its disengaged (extended) position blocks the drive in both directions of rotation, wherein the counter-abutment means connected with the toothed ring (16) are constructed as circumference steps (31,32) of a blocking ring (28), which is journalled rotatably and concentrically to the shaft (1) in the rose (7), is provided with a radial groove (35) into which an entraining pin (36) fixed to the toothed ring (16) engages, and is equipped, between the circumference steps (31,32), with an annular shoulder (33), which is interrupted at a fixed position, corresponding to the zero setting, and possibly also at least one further position for the passage of the blocking pin (19), wherein furthermore the blocking pin (19), provided with a rotation preventer, possesses a transverse recess (23) for engagement with the annular shoulder (33), wherein finally an actuating element (45), displaceably guided towards the rose (7) is disposed in the crank base (4), which (actuating element) can be brought by rotation of the actuating crank into alignment with the blocking pin (19), with the result that, on actuation, the blocking pin 919), at the specific positions at which the annular shoulder (33) is interrupted, can be engaged (retracted) into the path of the counter-abutment means, such devices are disclosed in the specifications of DT 23 33 666 C3; DE 40 26 754 C1 and U.S. Pat. No. 3,948,119, GB Patent 1 450 229 and GB 2 247 916A. With these well-proven devices it is possible to carry out two different movement sequences with the same shaft, namely optionally sliding or pivoting-out/pivoting-in respectively of the sliding lid in sliding-tilting roofs, in spite of the different setting displacements for these two movement sequences of different lengths, which are to be limited by means of the device.
In one of the known devices as disclosed in DT 23 33 666 C3, starting from only one indexing or zero setting in which the blocking pin can be actuated, at the commencement of one of the two movement sequences, or in transition from one movement sequence to the other, for example the transition from the sliding movement after the roof has been closed into the outward pivotal movement, the blocking pin simply needs to be engaged into the path of the abutment means connected with the toothed ring in order to cancel out the rotational blocking. The blocking ring here fulfills two functions, namely on the one hand it carries the displacement-limiting abutment means and on the other hand it firmly holds with its annular shoulder the engaged blocking pin, so that the drive can be actuated in both directions of rotation. Disengagement of the blocking pin for blocking the rotational movements is possible here at only one single position, that is when the lid-closed position has been reached. Along the entire travel of the lid closure and outward pivotal movement, the blocking pin remains engaged, so that intermediate positions cannot be blocked.
In the other known device as disclosed in DE 40 26 754 C1, in contrast, the annular shoulder of the blocking ring is provided with at least one further gap to permit passage of the blocking pin, so that at least one further, specified intermediate position of the lid is made possible, in which the drive is rotationally blocked and the lid is effectively secured against undesired sliding or pivoting movements. This rotational blocking and securing takes place as in the zero setting, if the blocking pin is opposite a further gap in the annular shoulder of the blocking ring, so that the blocking pin, as a consequence of the spring force acting on it, can be displaced for blocking the rotary drive.
In both the known forms of embodiment of the device, the actuating element disposed in the crank base for actuating the blocking pin is constructed as a detent bolt, is disposed coaxially to the blocking pin and slidably guided in a detent bushing of the crank base. The detent bolt is displaceable between two detent positions and can be actuated by means of an actuating knob fixed to it. If rotational blockings of the shaft are to be canceled, then with this arrangement of the device the actuating knob has to be pressed in each time. Desired sliding lid movements therefore require an actuation of the knob and the foldable actuating crank. These two actuating steps do not create any difficulty given the ergonomically favorable design of the actuating crank and are rapidly mastered by the users of the vehicle, but in the course of progressively advancing requirements for operating convenience a further simplification is desirable.
An object of the present invention therefore is so to construct a device of the initially named category wherein all actuations can be carried out exclusively by movements of the actuating crank.